R. f. half-wave pulse rectifier



Nov. 25, 19555 w. NEUGEBAUER 2,862,118

R. F. HALF-WAVE PULSE RECTIFIER Filed Oct. 2, 1957 /4 [y 4 20 24 42x 24/24 vJ JUUUUL lNl/ENTOR WENDELL NEUGEBA um Q I BY MJW/ H/S ATTORNEYS United States Patent R. F. HALF-WAVE PULSE RECTIFIER Wendell Neugebauer, Schenectady, N. Y., assignor to genleral Electric Company, a corporation of New Application October 2, 1957, Serial No. 687,828

13 Claims. (Cl. 307-449) This invention relates to half-wave radio frequency pulse rectifiers and particularly such rectifiers including a linear reject.

It is an object of the present invention to provide an improved half-wave radio frequency pulse rectifier and particularly a rectifier of the type set forth which can positively reject any desired portion of the input pulse.

Another object of the invention is to provide a rectifier -of the type set forth which includes means to minimize or eliminate the effect of the capacitance of the rectifying element when the rectifying element is operating in the high resistance direction.

Yet another object of the invention is to provide a halfwave radio frequency pulse rectifier including a plurality of rectifying units connected in cascade whereby to provide good rectification at the higher frequencies such as up through frequencies of the order of five megacycles.

Still another object of the invention is to provide a rectifier of the type set forth, the operation of which is independent of frequency of the applied pulse over a frequency range of from about one kilocycle to about five megacycles.

Yet another object of the invention is to provide a rectifier of the type set forth which provides good overall gain, for example, in the order of 0.9 or better.

Still another object of the invention is to provide a rectifier including a plurality of rectifying units connected in cascade, each rectifying unit carrying an equal share of the applied voltage which is to be clipped.

Yet another object of the invention is to provide a rectifier of the type set forth including a plurality of rectifying units connected in cascade, in which each rectifying unit is provided with a shunting member which effectively shunts the undesired portion of the output to radio frequency ground.

Still another object of the invention is to provide an improved rectifier of the type set forth which does not pass DC voltages.

Yet another object of the invention is to provide a rectifier including a plurality of rectifying units and including therein a control circuit to reject a predetermined portion of the input pulse in which the control voltage necessary to establish the reject level can have a small range of adjustability and still achieve a substantial range of control over the amount of the input pulse to be rejected.

Still another object of the invention is to provide a rectifier unit of the type set forth provided with a DC control source to be used in rejecting a predetermined portion of the input pulse, wherein the current drawn from the DC control source is small.

A further object of the invention is to provide a recti- 'fying circuit of the type set forth in which two separate DC control circuits are employed with two oppositely poled rectifying units whereby to pass any desired portion of the input pulse while positively rejecting the remaining portions of the input pulse.

These and other objects and advantages of the inven- 2,862,118 Patented Nov. 25, 1958 tion will be better understood from the following description when taken in conjunction with the accompanying drawing. In the drawing wherein like reference numerals have been designated to like parts:

Figure 1 is an electrical schematic diagram of one preferred form of half-wave radio frequency pulse rectifier made in accordance with and embodying the principles of the present invention, the rectifier including a plurality of rectifying units connected in cascade and provided with a common D. C. reject control voltage; and

Fig. 2 is an electrical schematic diagram of another embodiment of the present invention and illustrating the use of two oppositely poled rectifying units connected in cascade with separate control voltages whereby to permit rejection of both more negative portions of the input pulse and more positive portions of the input pulse.

Referring now to Fig. 1 of the drawings, there is shown an improved half-wave radio frequency pulse rectifier generally designated by the numeral 10 made in accordance with and embodying the principles of the present invention and including a reject control circuit. Rectifier 10 is provided with an input circuit including an input terminal 12 connected to a source of radio frequency pulses such as those diagrammatically illustrated at 14. Input terminal 12 connects with an input capacitor 16 which is useful to block any D. C. potential on terminal 12. The other terminal of capacitor 16 is connected to an input resistor 18 which is connected from a point 2%) to ground. Connection point 20 is also connected to one terminal of a rectifying element 22 which has been indicated as being of the crystal diode type. The other terminal of diode 22 is connected to a point 24. Diode 22 is poled to provide a low impedance when a potential is applied to cause conduction and flow of current from point 20 to point 24 and to have a high impedance when the potentials are such as to tend to cause conduction and flow of current from point 24 to point Ztl. From the above it will be seen that diode 22 is connected so that when the R. F. pulse 14 is applied thereto, a positive going half-wave rectified wave form is developed at point 24.

Although diode 22 has a substantially higher resistance to conduction from point 24 to point 20 as compared with the resistance when conducting from point 20 to point 24, there is still a small amount of conduction from point 24 to point 20 whereby to give a small negative going portion of the rectified wave form at point 24. Furthermore, at the higher R. F. frequencies diode 22 has an appreciable capacitance which tends to produce a negative going portion on the wave form at point 24. The effect of the inverse resistance and the capacitance of diode 22 can be substantially reduced by providing a shunt to radio frequency ground in the form of a second crystal diode 26. Diode 26 has one terminal thereof connected to point 24 and has the other terminal thereof connected through a capacitor 28 to radio frequency ground. It Will be seen that diode 26 is poled to be conducting and to have a low resistance when diode 22 is in the nonconducting condition. Accordingly, any negative going portion of the wave form appearing at point 24 will be shunted to radio frequency ground through diode 26 and the capacitor 28. As a result, the negative going portion of the wave form at point 24 will be substantially reduced.

Means has also been provided to control the voltage below which a portion of the input R. F. pulse 14 is rejected. This control of the level of rejection is accomplished by connecting a D. C. potential to the lower terminal of diode 26. More specifically, line 30 which is connected to the junction between diode 26 and capacitor 28 has applied thereto an adjustable D. C. potential. This D. C. potential is derived from any suitable potential source, the potential source in Fig. 1 being illustrated as a pair of batteries 32 and 34 connected in series whereby to add the potentials thereof with the junction 36 therebetween grounded. The other terminals of batteries 32 and 34 are connected to resistors 56 and 58 respectively, which in turn are connected to a resistor 38 having a movable contact 40 making connection therewith and connected to line 30. By moving contact 40 along resistor 38 and choosing suitable values for resistors 56 and 58, any desired D. C. control potential within the range of the potential of the batteries 32 and 34 can be applied to line 39. This D. C. control potential may be ground or may be negative or may be positive with respect to ground.

The diode 26 and the resistor 54 act as a load resistance for the rectifying diode 22. Accordingly, the potential below which any portion of R. F. wave form 14 can be rejected is readily adjustable by moving contact 49 along resistor 38.

The complete rectifier 10 is actually composed of several rectifying units connected in cascade. More specifically, the capacitor 16, the resistors 18 and 54, and the diodes 22 and 26 form a rectifying unit generally designated by the numeral 42 and enclosed within the dashed lines in Fig. 1. Two additional rectifying units 44 and 46 identical to rectifier unit 42 are connected in cascade therewith. Since rectifier units 42, 44 and 46 are identical, the same reference numerals have been applied to the individual circuit components thereof. The output from the rectifier 42 appearing at the point 24 is applied as the input to the rectifier unit 44 and particularly to the input capacitor 16 thereof. Likewise, the output from the point 24 of the rectifier unit 44 is connected as the input to the capacitor 16 of the rectifier unit 46. The output from the point 24 of the rectifier unit 46 is connected to an output terminal 4% which cooperates with a grounded output terminal 50. Accordingly, the output from the rectifier It is available between the terminals 48 and 50.

The use of several rectifier units in cascade is particularly desirable at the higher operating frequencies. As will be understood, the capacitive reactances of the rectifying elements such as the diodes 22 and 26 are substantially higher at the higher radio frequencies. In order to obtain satisfactory rejection, it is desirable to connect several rectifier units in cascade as is illustrated in Fig. 1 of the drawings. Each of the rectifier units 42, 44 and 46 has the lower terminal of the diode 26 and the resistor 54 thereof connected to the common line 30. Line 34 has a single D. C. control voltage applied thereto as has been explained above with respect to rectifier unit 42. Line 30 is also held at radio frequency ground by the capacitor 28.

The output appearing at terminals 48 and 50 is a series of positive going radio frequency pulses having the lower voltage thereof at the reject potential established on line 30. There is substantially no negative going portion of the output wave form 52 below the reject potential on line 349. Since the potential of line 3% can be adjusted, any desired part of the input wave form 14 can be rejected and the remaining portion applied to the output terminals 48-5ti by rectifier 16). This desirable operation is obtained even at relatively high operating frequencies such as those in the order of megacycles. It has been found in fact that the rectifier in operation is independent of frequency over the range from about one kilocycle to about five megacycles. The circuit gives a good gain, the gain being 0.9 or higher.

Each of rectifier units 42, 44 and 46 carries a sub stantially equal share of the R. F. voltage of input pulse 14- .which is rejected by rectifier it). The circuit positively does not pass D. C. voltage. A wide range of control over the level of reject can be achieved with a relatively small D. C. control voltage from batteries 32 and 34 when a large number of rectifier units 42, 44 and 46 is utilized. The approximate range of .D. C. control voltage is equal to the peak to peak voltage of the input pulse 14 divided by the number of rectifier units in rectifier 10. The current drawn from the D. C. control source is also small. The current drawn can be expressed by the following equations:

For the D. C. potential at point 40 negative with respect to ground:

I: 7'LV40 RIJRM R R 18+ f+ 6+ R54 For the D. C. potential at point 40 positive with respect to ground:

where I is the current drawn from the D. C. control source;

V is the D. C. control voltage at point 40;

n is the number of rectifier units;

R and R are the back and forward resistances of the diodes, R usually being very large;

R is the value of the resistor 18;

R is the value of the resistor 54.

It has been found that a suitable operation of the rectifier 10 is obtained with an input pulse not greater than 450 volts peak to peak when the various component parts thereof have the following values:

Capacitor 16 0.1 mf. Resistor 18 330K. Resistor 54 51K. Diodes 22 and 26 1N93. Capacitor 28 2 mf. Resistor 38 250K. Resistor 56 12K. Resistor 58 12K. Batteries 32 and 34 255 volts.

In the circuit of Fig. 1, the main rectifying diode 22 has been shown poled to pass the positive portion of the input pulse 14 and to reject the negative portions thereof. By reversing the connections for the diodes 22 and 26, the rectifying circuits will pass the negative going portions of the input pulse 14 and reject the positive going portions thereof above a selected potential determined by the reject D. C. control potential on line 30. Such an arrangement is illustrated in the right hand portion of Fig. 2 wherein rectifier units, generally designated by the numeral 60, have been shown connected in such a manner. The circuit when so connected possesses all of the advantages of the circuit of Fig. 1.

It is furthermore possible to reject any portion of input pulse 14 below a certain predetermined D. C. control potential and to reject any portion of the input pulse 14 above a second predetermined D. C. control potential. This can be accomplished by connecting a negative rejecting rectifying unit such as unit 42 in cascade with a positive rejecting rectifier unit such as unit 60. Such a circuit is illustrated in Fig. 2 of the drawings, two of the negative rejecting units 42 having been shown connected in cascade with two of the positive going rejecting units 60. it will be seen that the negative reject rectifier units 42 are connected to a suitable D. C. control source 62 whereby to establish the potential such as indicated by the numeral 64 below which no signal is passed. The positive going reject rectifier units 60 are provided with a separate D. C. control voltage source 66 which can be used to establish the potential 68 above which the portion of input pulse 14 will be rejected. Accordingly, there appears on the output terminals 70 of the rectifier of Fig. 3, an output which is only that portion of input pulse 14 appearing between the upper reject voltage from source 66 andthe lower reject voltage from source 62.

Other rectifying devices besides the crystal diodes described above can be utilized in the rectifier of the present invention. More specifically, thermionic diodes including high vacuum diodes and other forms of rectifier elements can be successfully utilized in the present invention.

It will be seen that there has been provided a rectifier with adjustable reject control which fulfills all of the objects and advantages set forth above. Although certain preferred forms of invention have been illustrated and described, it is to be understood that various changes and modifications can be made therein without departing from the spirit and scope of the invention. Accordingly, the invention is to be limited only as set forth in the following claims.

What is claimed is:

1. A pulse rectifier comprising a source of pulses, a first rectifying device having two terminals, a second rectifying device having two terminals, one set of the like terminals of said rectifying devices being connected together, the other terminal of said first rectifying device being coupled to said source of pulses, the other terminal of said second rectifying device being connected to a source of control voltage, a shunt resistor connected across said second rectifying device, a by-pass capacitor for the pulses connected to by-pass said source of control potential, and an output connection for the rectified pulses at the junction of said like terminals.

2. A pulse rectifier comprising a source of pulses, an input capacitor having one terminal thereof connected to said source of pulses, an input resistance having one end thereof connected to the other terminal of said input capacitor and having the other end thereof connected to ground, a first rectifying device having two terminals, a second rectifying device having two terminals, one set of like terminals of said rectifying devices being connected together, the other terminal of said first rectifying device being connected to the junction of said input capacitor and said input resistance, the other terminal of said second rectifying device being connected to a source of control voltage, a shunt resistor connected across said second rectifying device, a by-pass capacitor for the pulses connected to by-pass said source of control potential and an output connection for the rectified pulses at the junction of said like terminals.

3. A pulse rectifier as set forth in claim 2, wherein the control voltage is adjustable whereby to cause the rectifier to reject any desired portion of the input pulses.

4. A pulse rectifier as set forth in claim 3, wherein the rectifying devices are crystal diodes.

5. A pulse rectifier as set forth in claim 4, wherein the rectifying devices are poled to provide a positive going output from the rectifier.

6. A pulse rectifier as set forth in claim 4, wherein the rectifying devices are poled to provide a negative going output from the rectifier.

7. A radio frequency pulse rectifier comprising a source of pulses, a plurality of rectifier units connected in cascade, a common source of an adjustable control voltage for each of said rectifier units, a by-pass capacitor for the pulses connected to by-pass said source of control potential, each rectifier unit including an input capacitor having one terminal thereof connected to said source of pulses, an input resistance having one end thereof connected to the other terminal of said input capacitor and having the other end thereof connected to ground, a first rectifying device having two terminals, a second rectifying device having two terminals, one set of the like terminals of said rectifying devices being connected together, the other terminal of said first rectifying device in the first rectifier unit being coupled to the junction of said input capacitor and said input resistance, the other terminal of each said second rectifying devices being connected to said common source of control voltage, a shunt resistor connected across said second rectifying device, the output of each rectifier unit being at the junction of said rectifying devices and the input to each rectifying unit being the one terminal of said input capacitor.

8. A radio frequency pulse rectifier as set forth in claim 7, wherein the rectifying devices are poled to provide positive going outputs.

9. A radio frequency pulse rectifier as set forth in claim 7, wherein the rectifying devices are poled to provide a negative going output.

10. A radio frequency pulse rectifier comprising a source of radio frequency pulses, a first rectifier unit including a first input capacitor having one terminal thereof connected to said source of pulses, a first input resistance having one end thereof connected to the other terminal of said first input capacitor and having the other end thereof connected to ground, a first rectifying device having two terminals, a second rectifying device having two terminals, one set of the like terminals of said rectifying devices being connected together, the other terminal of said first rectifying device being coupled to the junction of said first input capacitor and said first input resistor, the other terminal of said second rectifying device being connected to a first source of control voltage, a shunt resistor connected across said second rectifying device, a first by-pass capacitor for the pulses connected to by-pass said first source of control potential, an output connection at the junction of said like terminals, a second rectifier unit including a second input capacitor having one terminal thereof coupled to said output connection, a second input resistance having one end thereof connected to the other terminal of said second input capacitor and having the other end thereof connected to ground, a third rectifying device having two terminals, a fourth rectifying device having two terminals, one set of the like terminals of said third and fourth rectifying devices being connected together, the other terminal of said third rectifying device being coupled to the junction of said second input capacitor and said second input resistor, the other terminal of said fourth rectifying device being connected to a second source of control voltage, a shunt resistor being connected across said fourth rectifying device, a second by-pass' capacitor for the pulses connected to by-pass said second source of control potential, and a second output connection for the rectified pulses at the junction of said like terminals of said third and fourth rectifying devices, said first and third rectifying devices being oppositely poled, said second and fourth rectifying devices being oppositely poled.

11. A radio frequency pulse rectifier as set forth in claim 10, wherein the sources of control potential are variable and are variable independently of each other.

12. A radio frequency pulse rectifier as set forth in claim 10, wherein at least two of the first rectifier units are provided and connected in cascade with the other terminal of the second rectifying devices thereof connected to the first source of control potention, and at least two of the second rectifier units are provided and are connected in cascade, the other terminal of the fourth rectifying devices thereof being connected to the second source of control potential.

13. A radio frequency pulse rectifier as set forth in claim 12, wherein the first rectifying units are poled to provide a positive going output and the second rectifying units are poled to provide a negative going output.

No references cited. 

